Associated Press file photoFederal officials say the dreaded Asian carp may have breached an electronic barrier designed to prevent it from invading the Great Lakes and threatening a $7 billion sport fishery.

Officials with the Army Corps of Engineer say Friday that DNA of the giant carp have been found north of the barrier in the Chicago Sanitary and Ship Canal.

If correct, that would mean the carp might reach Lake Michigan if they get through a navigational lock. From there, they could spread throughout the Great Lakes and out-compete native species for food.

Alan Steinman — head of the Grand Valley State University’s Annis Water Resources Institute in Muskegon — said no one knows if the dire predictions of Asian carp in Lake Michigan are correct, but if the fish is to be stopped now is the time.

Asian carp escaped from southern fish farms in the 1990s and have been migrating up the Mississippi and Illinois rivers. They can exceed 4 feet in length and 100 pounds.

Fisheries officials in Illinois initially reported that six miles of the Chicago Sanitary and Ship Canal would be treated with Rotenone, a chemical that will kill the fish by suffocation, depleting the waters of oxygen.

The latest report is that the fish-kill plan has been expanded to include a Rotenone application in waters upstream of the barrier. That means 20 miles downstream from Lake Michigan.

Steinman said that the Asian carp is a different beast from the other invasive species that entered and spread through the Great Lakes in the ballast water of commercial ships. These fish would have to naturally migrate, he said.

Despite the ability of one variety of the carp to jump out of the water, threatening anglers in small boats, the fish would pose no threat to swimmers, Steinman said. These are plant eaters not carnivores, he said.

However, the Asian carp is an aggressive competitor for plankton and could easily move aside other native fish species relying on the same food chain, Steinman said. The Asian carp would only harm fish populations in the shallower waters where they feed on plankton.